1. Field of the Invention
The instant disclosure relates to a flexible micro-system and fabrication method thereof; in particular, a flexible micro-system and fabrication method thereof based on a wafer-level integration process of bonding chip(s) onto a flexible substrate.
2. Description of the Related Art
Flexible electronics has been a popular research topic in recent years. Flexible electronics is a technological breakthrough over the traditional solid silicon based electronics technology. In expanding the flexibility of the electronics, flexible electronics can be effectively applied in applications that require flexibility and space saving. Moreover, comparing to traditional silicon based electronics, flexible electronics enjoys the advantage of lower production cost.
Temperature is a critical factor in the fabrication process of the flexible electronic system. The entire operating temperature of the fabrication process must be lower than the glass transition temperature of the flexible substrate. Under the above constraint, conventional fabrication techniques such as SOL active layer transfer, ultra-thin chip embedding, and amorphous silicon transistor are developed for the fabrication of flexible electronics. However, these conventional fabrication processes are generally complex and expensive with low convertibility and product quality.
An alternative technology called “heterogeneous chip assembly scheme” uses solder balls or anisotropic conductive adhesives for chip integration to the flexible substrate. However, solder balls may leave gaps between the chip and the substrate. Moreover, the anisotropic conductive adhesive has very high electrical resistance, which has adverse effect on the high-frequency operation of the micro-system.
With the required temperature constraint, the attainment of a standardized fabrication process for flexible electronics is highly desirable.
Based on related research and experience, the inventor proposes the following solution to address the above issues.